A V4 submersible pump is built for a 4-inch borewell and a V6 borewell pump for a 6-inch borewell. The number is the borewell casing diameter in inches. The horsepower, such as 1 hp, is a separate choice that depends on how much water you need and how high it must go.
Buy the diameter first, because it is fixed by your borewell. Then choose the horsepower from your required flow and total head.
What do V4 and V6 mean for a borewell?
The pump must fit inside the borewell casing with enough clearance to be lowered and lifted. A 4-inch pump suits a 4-inch (about 100 mm) bore, and a 6-inch pump suits a 6-inch (about 150 mm) bore. Using a pump that is too small in diameter for a wide bore is possible but the water flow around the motor, which cools it, differs.
Larger bores generally allow bigger motors and more stages. Check the maker's data sheet for the casing diameter, since naming differs between makers. If you are new to the types, read what openwell and borewell submersible pumps are.
What does 1 hp mean in a submersible pump?
One horsepower is about 0.75 kW of motor power. It tells you the size of the motor, not the water output. The same 1 hp motor can lift a little water from a great depth or more water from a shallow one, depending on the pump stages and impellers.
For that reason always read the performance curve. It plots flow against head for the pump. Choose a pump whose best efficiency point sits near your working flow and head.
How do you pick the right hp?
Gather the numbers below before you ask for a quote.
- The borewell diameter and depth.
- The static water level and the lowest level in dry season.
- The vertical lift from water to the outlet, plus the pipe length and friction losses.
- The flow you need in litres per minute or cubic metres per hour.
- The supply: single-phase or three-phase, voltage and frequency.
What else should be in the specification?
Specify the number of stages, impeller material, motor insulation class and cable length. The pump should also have a dry-run or overload protection method, usually through the control panel. See how to write a specification for a submersible pump for a full list.
Ask for the motor test results and the pump performance test. Compare them with the curve. If the maker cannot provide a test report from your batch, order a sample and have it tested.
Local rules for energy labelling and electrical safety differ by country. Confirm them with your importer or authority before ordering.
Ask also for the pump outlet size and thread, since the delivery pipe must match, and for the weight of the pump and its cable so you can plan the hoist or rope used to lower it. Check that the cable is rated for continuous submersion and long enough to reach the starter panel without joints.
Next step
We find pump makers in the Rajkot area, check samples on a test bench and supervise loading. Book a free sourcing review with your borewell details and duty point.